Doxorubicin-Loaded Thermoresponsive Superparamagnetic Nanocarriers for Controlled Drug Delivery and Magnetic Hyperthermia Applications

Core-Shell Magnetic Particles: Tailored Synthesis and Applications

Core-shell magnetic particles consisting of magnetic core and functional shells have aroused widespread attention in multidisciplinary fields spanning chemistry, materials science, physics, biomedicine, and bioengineering due to their distinctive magnetic properties, tunable interface features, and elaborately designed compositions. In recent decades, various surface engineering strategies have been developed to endow them desired properties (e.g., surface hydrophilicity, roughness, acidity, target recognition) for efficient applications in catalysis, optical modulation, environmental remediation, biomedicine, etc. Moreover, precise control over the shell structure features like thickness, porosity, crystallinity and compositions including metal oxides, carbon, silica, polymers, and metal-organic frameworks (MOFs) has been developed as the major method to exploit new functional materials. In this review, we highlight the synthesis methods, regulating strategies, interface engineering, and applications of core-shell magnetic particles over the past half-century. The fundamental methodologies for controllable synthesis of core-shell magnetic materials with diverse organic, inorganic, or hybrid compositions, surface morphology, and interface property are thoroughly elucidated and summarized. In addition, the influences of the synthesis conditions on the physicochemical properties (e.g., dispersibility, stability, stimulus-responsiveness, and surface functionality) are also discussed to provide constructive insight and guidelines for designing core-shell magnetic particles in specific applications. The brand-new concept of "core-shell assembly chemistry" holds great application potential in bioimaging, diagnosis, micro/nanorobots, and smart catalysis. Finally, the remaining challenges, future research directions and new applications for the core-shell magnetic particles are predicted and proposed.

Temperature and Ultrasound-Responsive Nanoassemblies for Enhanced Organ Targeting and Reduced Cardiac Toxicity

Background

Biocompatible nanocarriers are widely employed as drug-delivery vehicles for treatment. Nevertheless, indiscriminate drug release, insufficient organ-specific targeting, and systemic toxicity hamper nanocarrier effectiveness. Stimuli-responsive nano-sized drug delivery systems (DDS) are an important strategy for enhancing drug delivery efficiency and reducing unexpected drug release.

Methods

This study introduces a temperature- and ultrasound-responsive nano-DDS in which the copolymer p-(MEO2MA-co-THPMA) is grafted onto mesoporous iron oxide nanoparticles (MIONs) to construct an MPL-p nano-DDS. The copolymer acts as a nanopore gatekeeper, assuming an open conformation at sub-physiological temperatures that allows drug encapsulation and a closed conformation at physiological temperatures that prevents unexpected drug release during circulation. Lactoferrin was conjugated to the nanoparticle surface via polyethylene glycol to gain organ-targeting ability. External ultrasonic irradiation of the nanoparticles in the targeted organs caused a conformational change of the copolymer and reopened the pores, facilitating controlled drug release.

Results

MPL-p exhibited excellent biocompatibility and rare drug release in circulation. When targeting delivery to the brain, ultrasound promoted the release of the loaded drugs in the brain without accumulation in other organs, avoiding the related adverse reactions, specifically those affecting the heart.

Conclusion

This study established a novel temperature- and ultrasound-responsive DDS that reduced systemic adverse reactions compared with traditional DDS, especially in the heart, and demonstrated excellent organ delivery efficiency.

Stimuli-Responsive Polymers at the Interface with Biology

There has been growing interest in polymeric systems that break down or undergo property changes in response to stimuli. Such polymers can play important roles in biological systems, where they can be used to control the release of therapeutics, modulate imaging signals, actuate movement, or direct the growth of cells. In this Perspective, after discussing the most important stimuli relevant to biological applications, we will present a selection of recent exciting developments. The growing importance of stimuli-responsive polysaccharides will be discussed, followed by a variety of stimuli-responsive polymeric systems for the delivery of small molecule drugs and nucleic acids. Switchable polymers for the emerging area of therapeutic response measurement in theranostics will be described. Then, the diverse functions that can be achieved using hydrogels cross-linked covalently, as well as by various dynamic approaches will be presented. Finally, we will discuss some of the challenges and future perspectives for the field.

The use of supramolecular systems in biomedical applications for antimicrobial properties, biocompatibility, and drug delivery

Supramolecular chemistry is versatile for developing stimuli-responsive, dynamic and multifunctional structures. In the context of biomedical engineering applications, supramolecular assemblies are particularly useful as coatings for they can closely mimic the natural structure and organisation of the extracellular matrix (ECM), they can also fabricate other complex systems like drug delivery systems and bioinks. In the current context of growing medical device-associated complications and the developments in the controlled drug delivery and regenerative medicine fields, supramolecular assemblies are becoming an indispensable part of the biomedical engineering arsenal. This review covers the different supramolecular assemblies in different biomedical applications with a specific focus on antimicrobial coatings, coatings that enhance biocompatibility, surface modifications on implantable medical devices, systems that promote therapeutic efficiency in cancer therapy, and the development of bioinks. The introduced supramolecular systems include multilayer coating by polyelectrolytes, polymers incorporated with nanoparticles, coating simulation of ECM, and drug delivery systems. A perspective on the application of supramolecular systems is also included.

Hyperthermic triggers for drug delivery platforms

Electromagnetic fields can penetrate aqueous media in a homogeneous and instantaneous way, without physical contact, independently of its temperature, pressure, agitation degree and without modifying their chemical compositions nor heat and mass transfer conditions. In addition, superparamagnetic biomaterials can interact with electromagnetic fields by absorbing electromagnetic energy and transforming it in localized heat with further diffusion to surrounding media. This paper is devoted to the exploration of the potential use of hyperthermic effects resulting from the interaction between externally applied electromagnetic fields and superparamagnetic nanoparticles as a trigger for controlled drug release in soft tissue simulating materials. Gelatin based soft tissue simulating materials were prepared and doped with superparamagnetic nanoparticles. The materials were irradiated with externally applied electromagnetic fields. The effects on temperature and diffusion of a drug model in water and phosphate buffer were investigated. Significant hyperthermic effects were observed. The temperature of the soft tissue simulating material resulted increased from 35 °C to 45 °C at 2.5 °C min-1. Moreover, the release of an entrapped model drug reached 89%. The intensity of the hyperthermic effects was found to have a strong dependency on the concentration of superparamagnetic nanoparticles and the power and the pulse frequency of the electromagnetic field.

Stereo-Complex and Click-Chemical Bicrosslinked Amphiphilic Network Gels with Temperature/pH Response

Stimulus-responsive hydrogels have been widely used in the field of drug delivery because of their three-dimensional pore size and the ability to change the drug release rate with the change in external environment. In this paper, the temperature-sensitive monomer 2-methyl-2-acrylate-2-(2-methoxyethoxy-ethyl) ethyl ester (MEO2MA) and oligoethylene glycol methyl ether methacrylate (OEGMA) as well as the pH-sensitive monomer N,N-Diethylaminoethyl methacrylate (DEAEMA) were used to make the gel with temperature and pH response. Four kinds of physicochemical double-crosslinked amphiphilic co-network gels with different polymerization degrees were prepared by the one-pot method using the stereocomplex between polylactic acid as physical crosslinking and click chemistry as chemical crosslinking. By testing morphology, swelling, thermal stability and mechanical properties, the properties of the four hydrogels were compared. Finally, the drug release rate of the four gels was tested by UV-Vis spectrophotometer. It was found that the synthetic hydrogels had a good drug release rate and targeting, and had great application prospect in drug delivery.

Strategies for Targeted Delivery via Structurally Variant Polymeric Nanocarriers

The last decade has seen a meteoric rise in studies investigating polymeric aggregates as nanocarriers. When it comes to morphology, size, functionality, and immunostability, polymeric nanocarriers (PNCs) are unparalleled. With characteristics such as large surface area to volume ratio, amphiphilic nano‐environment, non‐toxic components, chemically modifiable composition, external surface alteration potential, uniform particle size, and stimuli‐dependent self‐assembly, PNCs have emerged as strong candidates for therapeutic applications. The article reviews the latest research on different challenges and strategies for targeted drug delivery and shall serve as guide to the researchers in designing site‐specific nanocarriers for application in future. The review systematically discusses the fundamental structural variation of the nanocarriers with emphasis on the influence of chemical alterations and the resulting effects on functionality; addresses the difficulties encountered with modes of administration; target selectivity and stimulus response.

How Magnetic Composites are Effective Anticancer Therapeutics? A Comprehensive Review of the Literature

Chemotherapy is the most prominent route in cancer therapy for prolonging the lifespan of cancer patients. However, its non-target specificity and the resulting off-target cytotoxicities have been reported. Recent in vitro and in vivo studies using magnetic nanocomposites (MNCs) for magnetothermal chemotherapy may potentially improve the therapeutic outcome by increasing the target selectivity. In this review, magnetic hyperthermia therapy and magnetic targeting using drug-loaded MNCs are revisited, focusing on magnetism, the fabrication and structures of magnetic nanoparticles, surface modifications, biocompatible coating, shape, size, and other important physicochemical properties of MNCs, along with the parameters of the hyperthermia therapy and external magnetic field. Due to the limited drug-loading capacity and low biocompatibility, the use of magnetic nanoparticles (MNPs) as drug delivery system has lost traction. In contrast, MNCs show higher biocompatibility, multifunctional physicochemical properties, high drug encapsulation, and multi-stages of controlled release for localized synergistic chemo-thermotherapy. Further, combining various forms of magnetic cores and pH-sensitive coating agents can generate a more robust pH, magneto, and thermo-responsive drug delivery system. Thus, MNCs are ideal candidate as smart and remotely guided drug delivery system due to a) their magneto effects and guide-ability by the external magnetic fields, b) on-demand drug release performance, and c) thermo-chemosensitization under an applied alternating magnetic field where the tumor is selectively incinerated without harming surrounding non-tumor tissues. Given the important effects of synthesis methods, surface modifications, and coating of MNCs on their anticancer properties, we reviewed the most recent studies on magnetic hyperthermia, targeted drug delivery systems in cancer therapy, and magnetothermal chemotherapy to provide insights on the current development of MNC-based anticancer nanocarrier.

Nanozymes with Peroxidase-like Activity for Ferroptosis-Driven Biocatalytic Nanotherapeutics of Glioblastoma Cancer: 2D and 3D Spheroids Models

Glioblastoma (GBM) is the most common primary brain cancer in adults. Despite the remarkable advancements in recent years in the realm of cancer diagnosis and therapy, regrettably, GBM remains the most lethal form of brain cancer. In this view, the fascinating area of nanotechnology has emerged as an innovative strategy for developing novel nanomaterials for cancer nanomedicine, such as artificial enzymes, termed nanozymes, with intrinsic enzyme-like activities. Therefore, this study reports for the first time the design, synthesis, and extensive characterization of innovative colloidal nanostructures made of cobalt-doped iron oxide nanoparticles chemically stabilized by a carboxymethylcellulose capping ligand (i.e., Co-MION), creating a peroxidase-like (POD) nanozyme for biocatalytically killing GBM cancer cells. These nanoconjugates were produced using a strictly green aqueous process under mild conditions to create non-toxic bioengineered nanotherapeutics against GBM cells. The nanozyme (Co-MION) showed a magnetite inorganic crystalline core with a uniform spherical morphology (diameter, 2R = 6-7 nm) stabilized by the CMC biopolymer, producing a hydrodynamic diameter (H_D) of 41-52 nm and a negatively charged surface (ZP~-50 mV). Thus, we created supramolecular water-dispersible colloidal nanostructures composed of an inorganic core (Cox-MION) and a surrounding biopolymer shell (CMC). The nanozymes confirmed the cytotoxicity evaluated by an MTT bioassay using a 2D culture in vitro of U87 brain cancer cells, which was concentration-dependent and boosted by increasing the cobalt-doping content in the nanosystems. Additionally, the results confirmed that the lethality of U87 brain cancer cells was predominantly caused by the production of toxic cell-damaging reactive oxygen species (ROS) through the in situ generation of hydroxyl radicals (·OH) by the peroxidase-like activity displayed by nanozymes. Thus, the nanozymes induced apoptosis (i.e., programmed cell death) and ferroptosis (i.e., lipid peroxidation) pathways by intracellular biocatalytic enzyme-like activity. More importantly, based on the 3D spheroids model, these nanozymes inhibited tumor growth and remarkably reduced the malignant tumor volume after the nanotherapeutic treatment (ΔV~40%). The kinetics of the anticancer activity of these novel nanotherapeutic agents decreased with the time of incubation of the GBM 3D models, indicating a similar trend commonly observed in tumor microenvironments (TMEs). Furthermore, the results demonstrated that the 2D in vitro model overestimated the relative efficiency of the anticancer agents (i.e., nanozymes and the DOX drug) compared to the 3D spheroid models. These findings are notable as they evidenced that the 3D spheroid model resembles more precisely the TME of "real" brain cancer tumors in patients than 2D cell cultures. Thus, based on our groundwork, 3D tumor spheroid models might be able to offer transitional systems between conventional 2D cell cultures and complex biological in vivo models for evaluating anticancer agents more precisely. These nanotherapeutics offer a wide avenue of opportunities to develop innovative nanomedicines for fighting against cancerous tumors and reducing the frequency of severe side effects in conventionally applied chemotherapy-based treatments.

Influence of the modifiers in polyol method on magnetically induced hyperthermia and biocompatibility of ultrafine magnetite nanoparticles

Magnetite nanoparticles (Fe₃O₄ NPs) are widely tested in various biomedical applications, including magnetically induced hyperthermia. In this study, the influence of the modifiers, i.e., urotropine, polyethylene glycol, and NH₄HCO_3, on the size, morphology, magnetically induced hyperthermia effect, and biocompatibility were tested for Fe₃O₄ NPs synthesized by polyol method. The nanoparticles were characterized by a spherical shape and similar size of around 10 nm. At the same time, their surface is functionalized by triethylene glycol or polyethylene glycol, depending on the modifiers. The Fe₃O₄ NPs synthesized in the presence of urotropine had the highest colloidal stability related to the high positive value of zeta potential (26.03 ± 0.55 mV) but were characterized by the lowest specific absorption rate (SAR) and intrinsic loss power (ILP). The highest potential in the hyperthermia applications have NPs synthesized using NH₄HCO₃, for which SAR and ILP were equal to 69.6 ± 5.2 W/g and 0.613 ± 0.051 nHm²/kg, respectively. Their application possibility was confirmed for a wide range of magnetic fields and by cytotoxicity tests. The absence of differences in toxicity to dermal fibroblasts between all studied NPs was confirmed. Additionally, no significant changes in the ultrastructure of fibroblast cells were observed apart from the gradual increase in the number of autophagous structures.

Development of stimuli responsive polymeric nanomedicines modulating tumor microenvironment for improved cancer therapy

The complexity of the tumor microenvironment (TME) severely hinders the therapeutic effects of various cancer treatment modalities. The TME differs from normal tissues owing to the presence of hypoxia, low pH, and immune-suppressive characteristics. Modulation of the TME to reverse tumor growth equilibrium is considered an effective way to treat tumors. Recently, polymeric nanomedicines have been widely used in cancer therapy, because their synthesis can be controlled and they are highly modifiable, and have demonstrated great potential to remodel the TME. In this review, we outline the application of various stimuli responsive polymeric nanomedicines to modulate the TME, aiming to provide insights for the design of the next generation of polymeric nanomedicines and promote the development of polymeric nanomedicines for cancer therapy.

Novel ABA block copolymers: preparation, temperature sensitivity, and drug release

A new PEGylated macroiniferter was prepared based on the polycondensation reaction of polyethylene oxide (PEO), methylene diphenyl diisocyanate (MDI), and 1,1,2,2-tetraphenyl-1,2-ethanediol (TPED). The macroiniferter consists of PEO end groups and readily reacts with acrylamides (such as N-isopropylacrylamide, NIPAM) and forms ABA block copolymers (PEO-PNIPAM-PEO). This approach of making amphiphilic ABA block copolymers is robust, versatile, and useful, particularly for the development of polymers for biomedical applications. The resulting amphiphilic PEO-PNIPAM-PEO block copolymers are also temperature sensitive, and their phase transition temperatures are close to human body temperature and therefore they have been applied as drug carriers for cancer treatment. Two PEO-PNIPAM-PEO polymers with different molecular weights were prepared and selected to make temperature-sensitive micelles. As a result of the biocompatibility of these micelles, cell viability tests proved that these micelles have low toxicity toward cancer cells. The resultant polymer micelles were then used as drug carriers to deliver the hydrophobic anticancer drug doxorubicin (DOX), and the results showed that they exhibit significantly higher cumulative drug release efficiency at higher temperatures. Moreover, after loading DOX into the micelles, cellular uptake experiments showed easy uptake and cell viability tests showed that DOX-loaded micelles possess a better therapeutic effect than free DOX at the same dose.

Enhanced tumor penetration for efficient chemotherapy by a magnetothermally sensitive micelle combined with magnetic targeting and magnetic hyperthermia

The high accumulation and poor penetration of nanocarriers in tumor is a contradiction of nanomedicine, which reduces the efficacy of chemotherapy. Due to the positive effect of hyperthermia on in vivo drug diffusion, we designed a magnetothermally sensitive micelle (MTM) by integrating magnetic targeting (MT), magnetic hyperthermia (MH), and magnetothermally responsive drug release to facilitate simultaneous drug accumulation and penetration in tumor. Accordingly, we synthesized a cyanine7-modified thermosensitive polymer with phase transition at 42.3°C, and utilized it to prepare drug-loaded MTMs by encapsulating superparamagnetic MnFe2O4 nanoparticles and doxorubicin (DOX). The obtained DOX–MTM had not only high contents of DOX (9.1%) and MnFe2O4 (38.7%), but also some advantages such as superparamagnetism, high saturation magnetization, excellent magnetocaloric effect, and magnetothermal-dependent drug release. Therefore, DOX–MTM improved in vitro DOX cytotoxicity by enhancing DOX endocytosis under the assistance of MH. Furthermore, MT and MH enhanced in vivo DOX–MTM accumulation and DOX penetration in tumor, respectively, substantially inhibiting tumor growth (84%) with excellent biosafety. These results indicate the development of an optimized drug delivery system with MH and MH-dependent drug release, introducing a feasible strategy to enhance the application of nanomedicines in tumor chemotherapy.

SPIONs Conjugate Supported Anticancer Drug Doxorubicin's Delivery: Current Status, Challenges, and Prospects

Considerable efforts have been directed towards development of nano-structured carriers to overcome the limitations of anticancer drug, doxorubicin's, delivery to various cancer sites. The drug's severe toxicity to cardio and hepatic systems, low therapeutic outcomes, inappropriate dose-demands, metastatic and general resistance, together with non-selectivity of the drug have led to the development of superparamagnetic iron oxide nanoparticles (SPIONs)-based drug delivery modules. Nano-scale polymeric co-encapsulation of the drug, doxorubicin, with SPIONs, the SPIONs surface end-groups' cappings with small molecular entities, as well as structural modifications of the SPIONs' surface-located functional end-groups, to attach the doxorubicin, have been achieved through chemical bonding by conjugation and cross-linking of natural and synthetic polymers, attachments of SPIONs made directly to the non-polymeric entities, and attachments made through mediation of molecular-spacer as well as non-spacer mediated attachments of several types of chemical entities, together with the physico-chemical bondings of the moieties, e.g., peptides, proteins, antibodies, antigens, aptamers, glycoproteins, and enzymes, etc. to the SPIONs which are capable of targeting multiple kinds of cancerous sites, have provided stable and functional SPIONs-based nano-carriers suitable for the systemic, and in vitro deliveries, together with being suitable for other biomedical/biotechnical applications. Together with the SPIONs inherent properties, and ability to respond to magnetic resonance, fluorescence-directed, dual-module, and molecular-level tumor imaging; as well as multi-modular cancer cell targeting; magnetic-field-inducible drug-elution capacity, and the SPIONs' magnetometry-led feasibility to reach cancer action sites have made sensing, imaging, and drug and other payloads deliveries to cancerous sites for cancer treatment a viable option. Innovations in the preparation of SPIONs-based delivery modules, as biocompatible carriers; development of delivery route modalities; approaches to enhancing their drug delivery-cum-bioavailability have explicitly established the SPIONs' versatility for oncological theranostics and imaging. The current review outlines the development of various SPIONs-based nano-carriers for targeted doxorubicin delivery to different cancer sites through multiple methods, modalities, and materials, wherein high-potential nano-structured platforms have been conceptualized, developed, and tested for, both, in vivo and in vitro conditions. The current state of the knowledge in this arena have provided definite dose-control, site-specificity, stability, transport feasibility, and effective onsite drug de-loading, however, with certain limitations, and these shortcomings have opened the field for further advancements by identifying the bottlenecks, suggestive and plausible remediation, as well as more clear directions for future development.

Smart and Multi-Functional Magnetic Nanoparticles for Cancer Treatment Applications: Clinical Challenges and Future Prospects

Iron oxide nanoparticle (IONPs) have become a subject of interest in various biomedical fields due to their magnetism and biocompatibility. They can be utilized as heat mediators in magnetic hyperthermia (MHT) or as contrast media in magnetic resonance imaging (MRI), and ultrasound (US). In addition, their high drug-loading capacity enabled them to be therapeutic agent transporters for malignancy treatment. Hence, smartening them allows for an intelligent controlled drug release (CDR) and targeted drug delivery (TDD). Smart magnetic nanoparticles (SMNPs) can overcome the impediments faced by classical chemo-treatment strategies, since they can be navigated and release drug via external or internal stimuli. Recently, they have been synchronized with other modalities, e.g., MRI, MHT, US, and for dual/multimodal theranostic applications in a single platform. Herein, we provide an overview of the attributes of MNPs for cancer theranostic application, fabrication procedures, surface coatings, targeting approaches, and recent advancement of SMNPs. Even though MNPs feature numerous privileges over chemotherapy agents, obstacles remain in clinical usage. This review in particular covers the clinical predicaments faced by SMNPs and future research scopes in the field of SMNPs for cancer theranostics.

Synthesis and Properties of Hydrogels on Medical Titanium Alloy Surface by Modified Dopamine Adhesion

Medical titanium alloy Ti-6Al-4V (TC4) is an ideal surgical implant material for human tissue repair and replacement. TC4 implantation will be in close contact with human soft tissue and has mechanical compatibility problems. In order to solve this problem, the hydrogel was formed on the surface of TC4 by utilizing the adhesion of dopamine, and the storage modulus of the formed hydrogel matched that of human soft tissue. In this paper, the surface of TC4 was first modified with dopamine (DA) and 2-bromoisobutyryl bromide (BIBB). 2-(2-methoxyethoxy) ethyl methacrylate (MEO₂MA), oligo (ethylene oxide) methacrylate (OEGMA) and 2-methacryloyloxyethyl phosphorylcholine (MPC) are used as monomers, and methylenebisacrylamide (MBA) is used as cross-linking agent. Thermosensitive hydrogels were formed on the surface of modified TC4 by the ATRP technique. The successful synthesis of initiator and hydrogels on TC4 was demonstrated by Fourier transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS). The morphology of the hydrogel was observed by the scanning electron microscope (SEM), and the water absorption and temperature sensitivity were investigated by the swelling property. The thermal and mechanical properties of these gels were measured using thermal analysis system (TAS) and dynamic mechanical analyzer (DMA). The results show that the hydrogel on TC4 has good thermal stability and storage modulus that matches human soft tissue.

Stimuli-Responsive Hybrid Metal Nanocomposite - A Promising Technology for Effective Anticancer Therapy

Cancer is one of the most challenging, life-threatening illnesses to cure, with over 10 million new cases diagnosed each year globally. Improved diagnostic cum treatment with common side-effects are warranting for successful therapy. Nanomaterials are recognized to improve early diagnosis, imaging, and treatment. Recently, multifunctional nanocomposites attracted considerable interest due to their low-cost production, and ideal thermal and chemical stability, and will be beneficial in future diagnostics and customized treatment capacity. Stimuli-Responsive Hybrid Metal Nanocomposites (SRHMNs) based nanocomposite materials pose the on/off delivery of bioactive compounds such as medications, genes, RNA, and DNA to specific tissue or organs and reduce toxicity. They simultaneously serve as sophisticated imaging and diagnostic tools when certain stimuli (e.g., temperature, pH, redox, ultrasound, or enzymes) activate the nanocomposite, resulting in the imaging-guided transport of the payload at defined sites. This review in detail addresses the recent advancements in the design and mechanism of internal breakdown processes of the functional moiety from stimuli-responsive systems in response to a range of stimuli coupled with metal nanoparticles. Also, it provides a thorough understanding of SRHMNs, enabling non-invasive interventional therapy by resolving several difficulties in cancer theranostics.

Local tumour nanoparticle thermal therapy: A promising immunomodulatory treatment for canine cancer

Distinct thermal therapies have been used for cancer therapy. For hyperthermia (HT) treatment the tumour tissue is heated to temperatures between 39 and 45°C, while during ablation (AB) temperatures above 50°C are achieved. HT is commonly used in combination with different treatment modalities, such as radiotherapy and chemotherapy, for better clinical outcomes. In contrast, AB is usually used as a single modality for direct tumour cell killing. Both thermal therapies have been shown to result in cytotoxicity as well as immune response stimulation. Immunogenic responses encompass the innate and adaptive immune systems and involve the activation of macrophages, dendritic cells, natural killer cells and T cells. Several heat technologies are used, but great interest arises from nanotechnology-based thermal therapies. Spontaneous tumours in dogs can be a model for cancer immunotherapies with several advantages. In addition, veterinary oncology represents a growing market with an important demand for new therapies. In this review, we will focus on nanoparticle-mediated thermal-induced immunogenic effects, the beneficial potential of integrating thermal nanomedicine with immunotherapies and the results of published works with thermotherapies for cancer using dogs with spontaneous tumours, highlighting the works that evaluated the effect on the immune system in order to show dogs with spontaneous cancer as a good model for evaluated the immunomodulatory effect of nanoparticle-mediated thermal therapies.

Investigation of Eutectic Mixtures of Fatty Acids as a Novel Construct for Temperature-Responsive Drug Delivery

Background

Most of the traditional nanocarriers of cancer therapeutic moieties present dose-related toxicities due to the uptake of chemotherapeutic agents in normal body cells. The severe life-threatening effects of systemic chemotherapy are well documented. Doxorubicin, DOX is the most effective antineoplastic agent but with the least specific action that is responsible for severe cardiotoxicity and myelosuppression that necessitates careful monitoring while administering. Stimuli-sensitive/intelligent drug delivery systems, specifically those utilizing temperature as an external stimulus to activate the release of encapsulated drugs, have become a subject of recent research. Thus, it would be ideal to have a nanocarrier comprising safe excipients and controllable drug release capacity to deliver the drug at a particular site to minimize unwanted and toxic effects of chemotherapeutics. We have developed a simple temperature-responsive nanocarrier based on eutectic mixture of fatty acids. This study aimed to develop, physicochemically characterize and investigate the biological safety of eutectic mixture of fatty acids as a novel construct for temperature-responsive drug release potential.

Methods

We have developed phase change material, PCM, based on a series of eutectic mixtures of fatty acids due to their unique and attractive physicochemical characteristics such as safety, stability, cost-effectiveness, and ease of availability. The reversible solid-liquid phase transition of PCM is responsible to hold firm or actively release the encapsulated drug. The eutectic mixtures of fatty acids (stearic acid and myristic acid) along with liquid lipid (oleic acid) were prepared to exhibit a tunable thermoresponsive platform. Doxorubicin-loaded lipid nanocarriers were successfully developed with combined hot melt encapsulation (HME) and sonication method and characterized to achieve enhanced permeability and retention (EPR) effect-based solid tumor targeting in response to exogenous temperature stimulus. The cytotoxicity against melanoma cell lines and in vivo safety studies in albino rats was also carried out.

Results

Doxorubicin-loaded lipid nanocarriers have a narrow size distribution (94.59-219.3 nm), and a PDI (0.160-0.479) as demonstrated by photon correlation microscopy and excellent colloidal stability (Z.P value: -22.7 to -32.0) was developed. Transmission electron microscopy revealed their spherical morphology and characteristics of a monodispersed system. A biphasic drug release pattern with a triggered drug release at 41°C and 43°C and a sustained drug release was observed at 37°C. The thermoresponsive cytotoxic potential was demonstrated in B16F10 cancer cell lines. Hemolysis assay and acute toxicity studies with drug-free and doxorubicin lipid nanocarrier formulations provided evidence for their non-toxic nature.

Conclusion

We have successfully developed a temperature-responsive tunable platform with excellent biocompatibility and intelligent drug release potential. The formulation components being from natural sources present superior characteristics in terms of cost, compatibility with normal body cells, and adaptability to preparation methods. The reported preparation method is adapted to avoid complex chemical processes and the use of organic solvents. The lipid nanocarriers with tunable thermoresponsive characteristics are promising biocompatible drug delivery systems for improved localized delivery of chemotherapeutic agents.

Hyperthermia-Induced In Situ Drug Amorphization by Superparamagnetic Nanoparticles in Oral Dosage Forms

Superparamagnetic iron oxide nanoparticles (SPIONs) generate heat upon exposure to an alternating magnetic field (AMF), which has been studied for hyperthermia treatment and triggered drug release. This study introduces a novel application of magnetic hyperthermia to induce amorphization of a poorly aqueous soluble drug, celecoxib, in situ in tablets for oral administration. Poor aqueous solubility of many drug candidates is a major hurdle in oral drug development. A novel approach to overcome this challenge is in situ amorphization of crystalline drugs. This method facilitates amorphization by molecular dispersion of the drug in a polymeric network inside a tablet, circumventing the physical instability encountered during the manufacturing and storage of conventional amorphous solid dispersions. However, the current shortcomings of this approach include low drug loading, toxicity of excipients, and drug degradation. Here, doped SPIONs produced by flame spray pyrolysis are compacted with polyvinylpyrrolidone and celecoxib and exposed to an AMF in solid state. A design of experiments approach was used to investigate the effects of SPION composition (Zn_0.5Fe_2.5O₄ and Mn_0.5Fe_2.5O₄), doped SPION content (10-20 wt %), drug load (30-50 wt %), and duration of AMF (3-15 min) on the degree of drug amorphization. The degree of amorphization is strongly linked to the maximum tablet temperature achieved during the AMF exposure (r = 0.96), which depends on the SPION composition and content in the tablets. Complete amorphization is achieved with 20 wt % Mn_0.5Fe_2.5O₄ and 30 wt % celecoxib in the tablets that reached the maximum temperature of 165.2 °C after 15 min of AMF exposure. Furthermore, manganese ferrite exhibits no toxicity in human intestinal Caco-2 cell lines. The resulting maximum solubility of in situ amorphized celecoxib is 5 times higher than that of crystalline celecoxib in biorelevant intestinal fluid. This demonstrates the promising capability of SPIONs as enabling excipients to magnetically induce amorphization in situ in oral dosage forms.

Fabrication of a magnetic nanocarrier for doxorubicin delivery based on hyperbranched polyglycerol and carboxymethyl cellulose: An investigation on the effect of borax cross-linker on pH-sensitivity

A new core-shell pH-responsive nanocarrier was prepared based on magnetic nanoparticle (MNP) core. Magnetic nanoparticles were first modified with hyperbranched polyglycerol as the first shell. Then the magnetic core was decorated with doxorubicin anticancer drug (DOX) and covered with PEGylated carboxymethylcellulose as the second shell. Borax was used to partially cross-link organic shells in order to evaluate drug loading content and pH-sensitivity. The structure of nanocarrier, organic shell loadings, magnetic responsibility, morphology, size, dispersibility, and drug loading content were investigated by IR, NMR, TG, VSM, XRD, DLS, HR-TEM and UV-Vis analyses. In vitro release investigations demonstrated that the use of borax as cross-linker between organic shells make the nanocarrier highly sensitive to pH so that more that 70% of DOX is released in acidic pH. A reverse pH-sensitivity was observed for the nanocarrier without borax cross-linker. The MTT assay determined that the nanocarrier exhibited excellent biocompatibility toward normal cells (HEK-293) and high toxicity against cancerous cells (HeLa). The nanocarrier also showed high hemocompatibility. Cellular uptake revealed high ability of nanocarrier toward HeLa cells comparable with free DOX. The results also suggested that low concentration of nanocarrier has a great potential for use as contrast agent in magnetic resonance imaging (MRI).

Advances in Intelligent-Responsive Nanocarriers for Cancer Therapy

With the rapid development of nanotechnology, strategies related to nanomedicine have been used to overcome the shortcomings of traditional chemotherapy drugs, thereby demonstrating significant potential for innovative drug delivery. Nanomaterials play an increasingly important role in cancer immunotherapy. Stimuli-responsive nanomaterials enable the precise control of drug release through exposure to specific stimuli and exhibit excellent specificity in response to various stimuli. Immunomodulators carried by nanomaterials can also effectively regulate the immune system and significantly improve their therapeutic effect on cancer. In recent years, stimuli-responsive nanomaterials have evolved rapidly from single stimuli-responsive systems to multi-stimuli-responsive systems. This review focuses on recent advances in the design and applications of stimuli-responsive nanomaterials, including exogenous and endogenous responsive nanoscale drug delivery systems, which show extraordinary potential in intelligent drug delivery for multimodal cancer diagnosis and treatment. Ultimately, the opportunities and challenges in the development of intelligent responsive nanomaterials are briefly discussed according to recent advances in multi-stimuli-responsive systems.

Evaluating magnetic and thermal effects of various Polymerylated magnetic iron oxide nanoparticles for combined chemo-hyperthermia

Killing cancer cells with heat: Assessing the heat-generation from Polymerylated magnetic iron oxide nanoparticles (PMNPs) for synergistic chemo-hyperthermia therapy.

An Efficient Carbon-Based Drug Delivery System for Cancer Therapy through the Nucleus Targeting and Mitochondria Mediated Apoptotic Pathway

The emergence of nanocarriers solves the problems of antitumor drugs such as non-targeting, huge side effects, etc., and has been widely used in tumor therapy. Some kinds of antitumor drugs such as doxorubicin (DOX) mainly act on the nucleic acid causing DNA damage, interfering with transcription, and thereby disrupting or blocking the process of cancer cell replication. Herein, a new nanodrug delivery system, the carbon-based nanomaterials (CBNs)-Pluronic F127-DOX (CPD), is designed by using CBNs as a nanocarrier for DOX. As a result, the tumor growth inhibition rate of CPD group is as high as 79.42 ± 2.83%, and greatly reduces the side effects. The targeting rate of the CPD group of DOX in the tumor nucleus is 36.78%, and the %ID/g in tumor tissue is 30.09%. The CPD regulates the expression levels of Caspase-3, p53, and Bcl-2 genes by increasing intracellular reactive oxygen species (ROS) levels and reducing mitochondrial membrane potential, which indicates that mitochondrial-mediated pathways are involved in apoptosis. The CPD nanodrug delivery system increases the effective accumulation of DOX in tumor cell nuclei and tumor tissues, and generates massive ROS, thereby inhibiting tumor growth in vivo, representing a promising agent for anticancer applications.

Drug release and magneto-calorific analysis of magnetic lipid microcapsules for potential cancer therapeutics

Magnetic nanoparticles (MNPs) with safety, stability and excellent magneto-calorific effect are the precondition for the smart magnetic drug carriers' fabrication and controllable drug release at a specific target in clinical treatment. In this study, the drug release and magneto-calorific effect of two types of magnetic lipid microcapsules (MLMs) loading lipid-coated MNPs and uncoated MNPs respectively were compared deeply in experimental analysis and theoretical simulation. The simulation results revealed that almost same magnetic heat effect and temperature increasing exist between lipid-coated and uncoated MNPs, which was consistent with the experimental drug release results. Coating lipid on MNPs didn't affect the magnetic heat and heat transfer of the MNPs. Because of the heat transfer between MNPs and water, MLMs and water around, the temperature increasing of whole sample solution is lower than that of the MNPs themselves. Our results provide a reliable theoretical basis for the development of healthy, safe, and biocompatible drug delivery systems.

Supramolecular magnetonanohybrids for multimodal targeted therapy of triple-negative breast cancer cells

Despite the undeniable advances in recent decades, cancer remains one of the deadliest diseases of the current millennium, where the triple-negative breast cancer (TNBC) is very aggressive, extremely metastatic, and resistant to conventional chemotherapy. The nanotheranostic approach focusing on targeting membrane receptors often expressed at abnormal levels by cancer cells can be a strategic weapon for fighting malignant tumors. Herein, we introduced a novel "all-in-one nanosoldier" made of colloidal hybrid nanostructures, which were designed for simultaneously targeting, imaging, and killing TNBC cells. These nanohybrids comprised four distinct components: (a) superparamagnetic iron oxide nanoparticles, as bi-functional nanomaterials for inducing ferroptosis via inorganic nanozyme-mediated catalysis and magnetotherapy by hyperthermia treatment; (b) carboxymethyl cellulose biopolymer, as a water-soluble capping macromolecule; (c) folic acid, as the membranotopic vector for targeting folate receptors; (d) and doxorubicin (DOX) drug for chemotherapy. The results demonstrated that this novel strategy was highly effective for targeting and killing TNBC cells in vitro, expressing high levels of folate membrane-receptors. The results evidenced that three integrated mechanisms triggered the deaths of the cancer cells in vitro: (a) ferroptosis, by magnetite nanoparticles inducing a Fenton-like reaction; (b) magneto-hyperthermia effect by generating heat under an alternate magnetic field; and (c) chemotherapy, through the DOX intracellular release causing DNA dysfunction. This "all-in-one nanosoldier" strategy offers a vast realm of prospective alternatives for attacking cancer cells, combining multimodal therapy and the delivery of therapeutic agents to diseased sites and preserving healthy cells, which is one of the most critical clinical challenges faced in fighting drug-resistant breast cancers.

Smart, Naturally-Derived Macromolecules for Controlled Drug Release

A series of troxerutin-based macromolecules with ten poly(acrylic acid) (PAA) or poly(2-dimethylaminoethyl methacrylate) (PDMAEMA) homopolymer side chains were synthesized by a supplemental activator and reducing agent atom transfer radical polymerization (SARA ATRP) approach. The prepared precisely-defined structures with low dispersity (M_w/M_n < 1.09 for PAA-based, and M_w/M_n < 1.71 for PDMAEMA-based macromolecules) exhibited pH-responsive behavior depending on the length of the polymer grafts. The properties of the received polyelectrolytes were investigated by dynamic light scattering (DLS) measurement to determine the hydrodynamic diameter and zeta potential upon pH changes. Additionally, PDMAEMA-based polymers showed thermoresponsive properties and exhibited phase transfer at a lower critical solution temperature (LCST). Thanks to polyelectrolyte characteristics, the prepared polymers were investigated as smart materials for controlled release of quercetin. The influence of the length of the polymer grafts for the quercetin release profile was examined by UV–VIS spectroscopy. The results suggest the strong correlation between the length of the polymer chains and the efficiency of active substance release, thus, the adjustment of the composition of the macromolecules characterized by branched architecture can precisely control the properties of smart delivery systems.

Synthesis of a thermoresponsive crosslinked MEO2MA polymer coating on microclusters of iron oxide nanoparticles

Encapsulation of magnetic nanoparticles (MNPs) of iron (II, III) oxide (Fe3O4) with a thermopolymeric shell of a crosslinked poly(2-(2-methoxyethoxy)ethyl methacrylate) P(MEO2MA) is successfully developed. Magnetic aggregates of large size, around 150-200 nm are obtained during the functionalization of the iron oxide NPs with vinyl groups by using 3-butenoic acid in the presence of a water soluble azo-initiator and a surfactant, at 70 °C. These polymerizable groups provide a covalent attachment of the P(MEO2MA) shell on the surface of the MNPs while a crosslinked network is achieved by including tetraethylene glycol dimethacrylate in the precipitation polymerization synthesis. Temperature control is used to modulate the swelling-to-collapse transition volume until a maximum of around 21:1 ratio between the expanded: shrunk states (from 364 to 144 nm in diameter) between 9 and 49 °C. The hybrid Fe3O4@P(MEO2MA) microgel exhibits a lower critical solution temperature of 21.9 °C below the corresponding value for P(MEO2MA) (bulk, 26 °C). The MEO2MA coating performance in the hybrid microgel is characterized by dynamic light scattering and transmission electron microscopy. The content of preformed MNPs [up to 30.2 (wt%) vs. microgel] was established by thermogravimetric analysis while magnetic properties by vibrating sample magnetometry.

Orienting the Pore Morphology of Core-Shell Magnetic Mesoporous Silica with the Sol-Gel Temperature. Influence on MRI and Magnetic Hyperthermia Properties

The controlled design of robust, well reproducible, and functional nanomaterials made according to simple processes is of key importance to envision future applications. In the field of porous materials, tuning nanoparticle features such as specific area, pore size and morphology by adjusting simple parameters such as pH, temperature or solvent is highly needed. In this work, we address the tunable control of the pore morphology of mesoporous silica (MS) nanoparticles (NPs) with the sol-gel reaction temperature (T_sg). We show that the pore morphology of MS NPs alone or of MS shell covering iron oxide nanoparticles (IO NPs) can be easily tailored with T_sg orienting either towards stellar (ST) morphology (large radial pore of around 10 nm) below 80 °C or towards a worm-like (WL) morphology (small randomly oriented pores channel network, of 3–4 nm pore size) above 80 °C. The relaxometric and magnetothermal features of IO@STMS or IO@WLMS core shell NPs having respectively stellar or worm-like morphologies are compared and discussed to understand the role of the pore structure for MRI and magnetic hyperthermia applications.

Facile design of gemini surfactant-like peptide for hydrophobic drug delivery and antimicrobial activity

Recently, many kinds of gemini-type amphiphilic peptides have been designed and shown their advantage as self-assembling nanomaterials. In this study, we proposed a simple strategy to design gemini surfactant-like peptides, which are only composed of natural amino acids and can be easily obtained by conventional peptide sythnesis. Taking two prolines as the turn-forming units, a peptide named APK was designed. The petide has a linear sequence but naturally takes the conformation like a gemini surfactant. Compared with a single-tailed surfactant-like peptide A6K, APK showed much stronger ability to undergo self-assembly and to encapsulate hydrophobic pyrene. Several hydrophobic drugs including paclitaxel, doxorubicin, etomidate and propofol were encapsulated by APK, and the corresponding formulations showed anti-tumor or anesthetic efficacy comparable to their respective clinical formulations. Furthermore, APK could inhibit the growth of different microorganisms including E. coli, S. aureus and C. albicans. Etomidate and propofol formulations encapsulated by APK also showed strong antimicrobial activity. Taking APK as an example, our study indicated a straightforward strategy to design gemini surfactant-like peptides, which could be potential nanomaterials for exploring hydrophobic drug formulations with efficacy, safety and self-antimicrobial activity.

Hyperthermia treatment of cancer cells by the application of targeted silk/iron oxide composite spheres

Magnetic iron oxide nanoparticles (IONPs) are one of the most extensively studied materials for theranostic applications. IONPs can be used for magnetic resonance imaging (MRI), delivery of therapeutics, and hyperthermia treatment. Silk is a biocompatible material and can be used for biomedical applications. Previously, we produced spheres made of H2.1MS1 bioengineered silk that specifically carried a drug to the Her2-overexpressing cancer cells. To confer biocompatibility and targeting properties to IONPs, we blended these particles with bioengineered spider silks. Three bioengineered silks (MS1Fe1, MS1Fe2, and MS1Fe1Fe2) functionalized with the adhesion peptides F1 and F2, were constructed and investigated to form the composite spheres with IONPs carrying a positive or negative charge. Due to its highest IONP content, MS1Fe1 silk was used to produce spheres from the H2.1MS1:MS1Fe silk blend to obtain a carrier with cell-targeting properties. Composite H2.1MS1:MS1Fe1/IONP spheres made of silks blended at different ratios were obtained. Although the increased content of MS1Fe1 silk in particles resulted in an increased affinity of the spheres to IONPs, it decreased the binding of the composite particles to cancer cells. The H2.1MS1:MS1Fe1 particles prepared at a ratio of 8:2 and loaded with IONPs exhibited the ability to bind to the targeted cancer cells similar to the control spheres without IONPs. Moreover, when exposed to the alternating magnetic field, these particles generated 2.5 times higher heat. They caused an almost three times higher percentage of apoptosis in cancer cells than the control particles. The blending of silks enabled the generation of cancer-targeting spheres with a high affinity for iron oxide nanoparticles, which can be used for anti-cancer hyperthermia therapy.

Advances and perspectives in carrier-free nanodrugs for cancer chemo-monotherapy and combination therapy

Nanocarrier-based drug delivery systems hold impressive promise for biomedical application because of their excellent water dispersibility, prolonged blood circulation time, increased drug accumulation in tumors, and potential in combination therapeutics. However, most nanocarriers suffer from low drug-loading efficiency, poor therapeutic effectiveness, potential systematic toxicity, and unstable metabolism. As an alternative, carrier-free nanodrugs, completely formulated with one or more drugs, have attracted increasing attention in cancer therapy due to their advantage of improved pharmacodynamics/pharmacokinetics, reduced toxicity, and high drug-loading. In recent years, carrier-free nanodrugs have contributed to progress in a variety of therapeutic modalities. In this review, different common strategies for carrier-free nanodrugs preparation are first summarized, mainly including nanoprecipitation, template-assisted nanoprecipitation, thin-film hydration, spray-drying technique, supercritical fluid (SCF) technique, and wet media milling. Then we describe the recently reported carrier-free nanodrugs for cancer chemo-monotherapy or combination therapy. The advantages of anti-cancer drugs combined with other chemotherapeutic, photosensitizers, photothermal, immunotherapeutic or gene drugs have been demonstrated. Finally, a future perspective is introduced to highlight the existing challenges and possible solutions toward clinical application of currently developed carrier-free nanodrugs, which may be instructive to the design of effective carrier-free regimens in the future.

Revealing the NIR-triggered chemotherapy therapeutic window of magnetic and thermoresponsive nanogels

The combination of magnetic nanoparticles and thermoresponsive nanogels represents an appealing strategy for the development of theranostic probes. These hybrid nanocarriers present several advantages such as outstanding properties for guided therapy, magnetic resonance imaging, and triggered release of encapsulated cargoes. Most magnetic thermoresponsive nanogels are built with strategies that comprise a physical interaction of particles with the polymeric network or the covalent attachment of a single particle to the linear polymer. Herein, we report a facile synthetic approach for the synthesis of magnetic and thermoresponsive nanogels that allows the controlled incorporation of multiple superparamagnetic inorganic cores as covalent cross-linkers. An ultrasonication-assisted precipitation-polymerization afforded nanogels with sizes in the nanometric range and similar magnetization and light transduction properties compared to the discrete magnetic nanoparticles. The theranostic capability of these nanocarriers was further investigated both in vitro and in vivo. In vivo experiments demonstrated the capacity of these materials as nanocarriers for near-infrared (NIR) triggered chemotherapy and highlighted the relevance of the correct concentration/dose in this antitumoral modality to achieve a superior therapeutic efficacy.

Enhanced In Vitro Magnetic Cell Targeting of Doxorubicin-Loaded Magnetic Liposomes for Localized Cancer Therapy

The lack of efficient targeting strategies poses significant limitations on the effectiveness of chemotherapeutic treatments. This issue also affects drug-loaded nanocarriers, reducing nanoparticles cancer cell uptake. We report on the fabrication and in vitro characterization of doxorubicin-loaded magnetic liposomes for localized treatment of liver malignancies. Colloidal stability, superparamagnetic behavior and efficient drug loading of our formulation were demonstrated. The application of an external magnetic field guaranteed enhanced nanocarriers cell uptake under cell medium flow in correspondence of a specific area, as we reported through in vitro investigation. A numerical model was used to validate experimental data of magnetic targeting, proving the possibility of accurately describing the targeting strategy and predict liposomes accumulation under different environmental conditions. Finally, in vitro studies on HepG2 cancer cells confirmed the cytotoxicity of drug-loaded magnetic liposomes, with cell viability reduction of about 50% and 80% after 24 h and 72 h of incubation, respectively. Conversely, plain nanocarriers showed no anti-proliferative effects, confirming the formulation safety. Overall, these results demonstrated significant targeting efficiency and anticancer activity of our nanocarriers and superparamagnetic nanoparticles entrapment could envision the theranostic potential of the formulation. The proposed magnetic targeting study could represent a valid tool for pre-clinical investigation regarding the effectiveness of magnetic drug targeting.

Meticulous Doxorubicin Release from pH-Responsive Nanoparticles Entrapped within an Injectable Thermoresponsive Depot

The dual stimuli-controlled release of doxorubicin from gel-embedded nanoparticles is reported. Non-cytotoxic polymer nanoparticles are formed from poly(ethylene glycol)-b-poly(benzyl glutamate) that, uniquely, contain a central ester link. This connection renders the nanoparticles pH-responsive, enabling extensive doxorubicin release in acidic solutions (pH 6.5), but not in solutions of physiological pH (pH 7.4). Doxorubicin-loaded nanoparticles were found to be stable for at least 31 days and lethal against the three breast cancer cell lines tested. Furthermore, doxorubicin-loaded nanoparticles could be incorporated within a thermoresponsive poly(2-hydroxypropyl methacrylate) gel depot, which forms immediately upon injection of poly(2-hydroxypropyl methacrylate) in dimethyl sulfoxide solution into aqueous solution. The combination of the poly(2-hydroxypropyl methacrylate) gel and poly(ethylene glycol)-b-poly(benzyl glutamate) nanoparticles yields an injectable doxorubicin delivery system that facilities near-complete drug release when maintained at elevated temperatures (37 °C) in acidic solution (pH 6.5). In contrast, negligible payload release occurs when the material is stored at room temperature in non-acidic solution (pH 7.4). The system has great potential as a vehicle for the prolonged, site-specific release of chemotherapeutics.

Fine tuning and optimization of magnetic hyperthermia treatments using versatile trapezoidal driving-field waveforms

Applying trapezoidal driving-field waveforms to activate magnetic nanoparticles optimizes their performance as heat generators in magnetic hyperthermia, with notable advantages with respect to the effects of harmonic magnetic fields of the same frequency and amplitude. A rate equation approach is used to determine the hysteretic properties and the power released by monodisperse and polydisperse magnetite nanoparticles with randomly oriented easy axes subjected to a radio-frequency trapezoidal driving field. The heating ability of the activated nanoparticles is investigated by means of a simple model in which the heat equation is solved in radial geometry with boundary conditions simulating in vivo applications. Changes of the inclination of the trapezoidal waveform's lateral sides are shown to induce controlled changes in the specific loss power generated by the activated nanoparticles. Specific issues typical of the therapeutic practice of hyperthermia, such as the need for fine tuning of the optimal treatment temperature in real time, the possibility of combining sequential treatments at different temperatures, and the ability to substantially reduce the heating transient in a hyperthermia treatment are suitably addressed and overcome by making use of versatile driving fields of a trapezoidal shape.

Recent Advances of Magnetic Nanomaterials in Bone Tissue Repair

The magnetic field has been proven to enhance bone tissue repair by affecting cell metabolic behavior. Magnetic nanoparticles are used as biomaterials due to their unique magnetic properties and good biocompatibility. Through endocytosis, entering the cell makes it easier to affect the physiological function of the cell. Once the magnetic particles are exposed to an external magnetic field, they will be rapidly magnetized. The magnetic particles and the magnetic field work together to enhance the effectiveness of their bone tissue repair treatment. This article reviews the common synthesis methods, the mechanism, and application of magnetic nanomaterials in the field of bone tissue repair.

pH-triggered intracellular release of doxorubicin by a poly(glycidyl methacrylate)-based double-shell magnetic nanocarrier

Two core-double-shell pH-sensitive nanocarriers were fabricated using Fe₃O₄ as magnetic core, poly(glycidyl methacrylate-PEG) and salep dialdehyde as the first and the second shell, and doxorubicin as the hydrophobic anticancer drug. Two nanocarriers were different in the drug loading steps. The interaction between the first and the second shell assumed to be pH-sensitive via acetal cross linkages. The structure of nanocarriers, organic shell loading, magnetic responsibility, morphology, size, dispersibility, and drug loading content were investigated by IR, NMR, TG, VSM, XRD, DLS, HRTEM and UV-Vis analyses. The long-term drug release profiles of both nanocarriers showed that the drug loading before cross-linking between the first and second shell led to a more pH-sensitive nanocarrier exhibiting higher control on DOX release. Cellular toxicity assay (MTT) showed that DOX-free nanocarrier is biocompatible having cell viability greater than 80% for HEK-293 and MCF-7 cell lines. Besides, high cytotoxic effect observed for drug-loaded nanocarrier on MCF-7 cancer cells. Cellular uptake analysis showed that the nanocarrier is able to transport DOX into the cytoplasm and perinuclear regions of MCF-7 cells. In vitro hemolysis and coagulation assays demonstrated high blood compatibility of nanocarrier. The results also suggested that low concentration of nanocarrier have a great potential as a contrast agent in magnetic resonance imaging (MRI).

NIR/Thermoresponsive Injectable Self-Healing Hydrogels Containing Polydopamine Nanoparticles for Efficient Synergistic Cancer Thermochemotherapy

Injectable and self-healing hydrogels with thermoresponsiveness as smart hydrogels displayed injectability, automatic healing, and phase and volume changes as well. Here, the thermoresponsive self-healing hydrogel was prepared via the formation of dynamic covalent enamine bonds between the amino groups in polyetherimide (PEI) and the acetoacetate groups in the four-armed star-shaped poly(2-(dimethylamino)ethyl methacrylate-co-2-hydroxyethyl methacrylate) modified with tert-butyl acetoacetate (t-BAA), SP(DMAEMA-co-HEMA-AA). After adding polydopamine nanoparticles (PDA NPs), the SP(DMAEMA-co-HEMA-AA)/PEI/PDA-NP nanocomposite hydrogel presented phase change and volume shrinkage under near-infrared (NIR) irradiation. The thermoresponsive nanocomposite hydrogel loaded with the anticancer drug doxorubicin (DOX) could be injected into the 4T1 tumor by intratumoral injection. After NIR laser irradiation, the temperature of the hydrogel increased because of the photothermal effect of PDA NPs inducing local hyperthermia. Because the hydrophilicity-hydrophobicity transition of the hydrogel occurred, DOX molecules were squeezed out from the hydrogel at temperatures higher than its lower critical solution temperature (LCST) and the tumor cells suffered from internal stress from the shrunk hydrogel. The injectable nanocomposite hydrogel not only demonstrated the synergism of highly efficient thermochemotherapy but also showed the function of improving drug utilization and precise treatment to reduce the side effects of drugs.

Multifunctional Nanoparticles for Multimodal Imaging-Guided Low-Intensity Focused Ultrasound/Immunosynergistic Retinoblastoma Therapy

Retinoblastoma (RB) is prone to delayed diagnosis or treatment and has an increased likelihood of metastasizing. Thus, it is crucial to perform an effective imaging examination and provide optimal treatment of RB to prevent metastasis. Nanoparticles that support diagnostic imaging and targeted therapy are expected to noninvasively integrate tumor diagnosis and treatment. Herein, we report a multifunctional nanoparticle for multimodal imaging-guided low-intensity focused ultrasound (LIFU)/immunosynergistic RB therapy. Magnetic hollow mesoporous gold nanocages (AuNCs) conjugated with Fe₃O₄ nanoparticles (AuNCs-Fe₃O₄) were prepared to encapsulate muramyl dipeptide (MDP) and perfluoropentane (PFP). The multimodal imaging capabilities, antitumor effects, and dendritic cell (DC) activation capacity of these nanoparticles combined with LIFU were explored in vitro and in vivo. The biosafety of AuNCs-Fe₃O₄/MDP/PFP was also evaluated systematically. The multifunctional magnetic nanoparticles enhanced photoacoustic (PA), ultrasound (US), and magnetic resonance (MR) imaging in vivo and in vitro, which was helpful for diagnosis and efficacy evaluation. Upon accumulation in tumors via a magnetic field, the nanoparticles underwent phase transition under LIFU irradiation and MDP was released. A combined effect of AuNCs-Fe₃O₄/MDP/PFP and LIFU was recorded and verified. AuNCs-Fe₃O₄/MDP/PFP enhanced the therapeutic effect of LIFU and led to direct apoptosis/necrosis of tumors, while MDP promoted DC maturation and activation and activated the ability of DCs to recognize and clear tumor cells. By enhancing PA/US/MR imaging and inhibiting tumor growth, the multifunctional AuNC-Fe₃O₄/MDP/PFP nanoparticles show great potential for multimodal imaging-guided LIFU/immunosynergistic therapy of RB. The proposed nanoplatform facilitates cancer theranostics with high biosafety.

Multi-stimuli-responsive nanomicelles fabricated using synthetic polymer polylysine conjugates for tumor microenvironment dependent drug delivery

A poly(lysine)-synthetic polymer hybrid nanomicelles were fabricated as promising platform for efficient tumor targeting and glutathione/pH/temperature-responsive anticancer drug delivery.